Physico-chemical parameters
Lake Colac and Tooliorook had the minimum salinity,Modewarre had the maximum and Bolac was intermediate.
Fluctuations in salinity were greatest in Lake Bolac and least in Lake Colac. Salinity showed weak seasonal fluctuations,
with values ranging from a minimum of 2 _+ 0.01 ppt
in Lake Colac to a maximum of 8 + 0.06 ppt in Lake Modewarre
(Fig. 2). Salinity was generally high in summer
(November-March) and low during winter (May-September).
Dissolved oxygen (DO) concentration in the lakes
ranged from a minimum of 7.8 _+ 0.2 to maximum of 10.1 +
0.05 mg 1 -I. DO showed little seasonal variation (Fig. 2).
Water temperature varied considerably between winter and
summer months, with values ranging from a minimum of
7.4 _+ 0.1 °C to a maximum of 23 + 0.1 °C (Fig. 2). The pattern
of changing mean monthly water temperature of the
lakes closely followed the air temperature, and therefore
showed marked seasonal differences.